This application is directed to multifunctional lubricant additives prepared by reaction of diorganophosphorodithioic acids and sulfurous oxyhalides, e.g., thionyl chloride which when incorporated into lubricating oils or greases, impart resistance to oxidation and abrasion and increase their service life. These materials are effective in hydrocarbon and synthetic, e.g., ester base stocks.
Zinc dithiophosphates (ZnDTP) have been used for several years in lubricating oils to which they impart multifunctional antiwear/antioxidant protection. However, in recent years, environmental and toxicological demands have created a need for their replacement because of disposal problems and deleterious effects on catalytic converters of automobile engines. Consequently, there have been strong efforts in the industry to find replacements for them. Copper salts of phosphorodithioic acids such as phosphorothionyl disulfide are known in the art; see, for example, U.S. Pat. No. 4,582,920. U.S. Pat. No. 4,405,470 discloses it is known to react a diorganodithiophosphoric acid ester with vinyl carboxylate. The product is described as being useful as an antioxidant in lubricants.
U.S. Pat. No. 3,644,206 discloses a product made by reacting a diorganodithiophosphoric acid with a cyclic hindered aldehyde. The product is useful as an antioxidant in various organic fluids.
U.S. Pat. Nos. 4,000,271; 4,405,470 and 4,582,617 disclose various products and compounds of organophosphorus having utility as deodorizers, greases and lubricants. U.S. Pat. No. 4,600,517 discloses grease formulations containing phosphorus and sulfur moieties.
It is one object of this invention to provide novel organic compositions which have improved oxidation stability and antiwear activity. It is a further object of this invention to provide novel compositions which afford protection against oxidation deterioration for organic media to which they have been added. Another object is to provide improved lubricating oil compositions capable of withstanding the oxidizing conditions of modern engines. These and other objects will become apparent from the following disclosure.
The non-metallic, ashless compounds or additive products described herein have shown very good antiwear/antioxidant effectiveness in lubricating oils and have the potential advantage of better compatibility with, and solubility in, a variety of base stocks.